1. Field of the Invention
This invention relates generally to musical instruments and, more particularly, to apparatus for sensing the manipulation of the musical apparatus having keys activating selected sounds or activities, such as the pianoforte, the clavichords and the like.
2. Discussion of the Related Art
It has been known in the related art to determine when a keyboard instrument such as piano, has a key or activation device manipulated by having a mechanical switching device associated with each key. The switching device, e.g. a microswitch, is responsive to the movement of the key, the movement changing microswitch contacts. The switching device suffers from several limitations. The first limitation is that the force necessary to activate the switching device can interfere with the manipulation of the keys of the instrument and provide a different responsiveness or "feel" to an operator of the associated key. Secondly, switching devices do not conveniently provide information with respect to the pressure by which the key has been activated.
Other methods of sensing the manipulation of the components of a keyboard or similar type of instrument includes coupling springs to the individual keys. The springs are associated with a sensing device and the sensing device can indicate to a controller the motion of the key. Other sensors can be coupled to the instrument components that produce the sound or activity activated by the keys. These transducers can indicate not only activation of a particular component, but with related complex apparatus, such as an optical sensing instrument, can indicate the force which the component has been activated.
These techniques for determining the manipulation of a keyboard are expensive and typically require elaborate implementation either during the manufacture of the musical instrument and an equal or greater effort to retrofit the sensing device in the musical instrument.
A need has therefore been felt for a sensing device for keys of a piano keyboard, or similar type instrument, to determine when the key is manipulated and the force with which the key is. In addition, a need was felt for a sensing device that can detect the manipulation of the keys of a keyboard and similar apparatus that is capable of being conveniently retrofitted to existing instruments.